Milk foaming machines already exist for a long time, being able to provide hot milk foams. These known machines use different types of foaming, heating and milk storing solutions. Professional milk foaming machines used in business applications are frequently used along the day: they typically comprise a metallic milk container, preferably made in stainless steel, where milk is stored and is kept refrigerated at a temperature typically of around 4° C. in order to correctly and hygienically preserve it until it is going to be used and delivered as milk foam. The problem is that, at the beginning of the day, milk is effectively at a low temperature of 4° C. but, as the day goes by, milk temperature increases and, either the container needs to be removed and stored in the fridge for some time, or milk temperature increases above the allowable limit (typically stablished at around 15° C.): in the first case, the system is not friendly for the user and, in the second case, hygiene problems may arise. Other solutions provide these machines with a compressor that keeps continuously refrigerated the milk container.
In these known milk foaming machines, milk is sucked through a flexible pipe and the air needed for foaming is provided through an air valve: the mixture of milk and air then typically flows through a labyrinth passage where it is foamed. Heating of the foam can be achieved by injecting steam into the mixture, in order to heat it. The problem of these known systems is that the parts (typically pipes or ducts) through which milk and air and steam are delivered need to be either made disposable, so that they are kept hygienic, but therefore provide a costly solution and not of friendly use, or if made cleanable, their cleaning is highly complicated.
Therefore, current known solutions in the state of the art have serious disadvantages in terms of user friendliness, handling and cleaning. As explained, typical professional solutions have a milk fridge (milk container that is kept refrigerated), a milk fluid system, optionally a milk heating system and a foaming device. All these existing solutions have the milk fluid system, the heating and the foaming device outside the refrigerated area, needing complex cleaning procedures after each foam preparation or at least after each day of use.
Document US 2004/0241297 A1 for example discloses a device for production and application of whipped cream: this device comprises a cream container from which liquid cream is supplied through a suction line into a foaming device from which foam is provided through a nozzle. In this device, only cold or chilled whipped cream can be provided as there are no heating means, and in order to hygienically preserve the cream remaining in the nozzle and/or foaming device between different uses of the machine, the nozzle and outlet head can be retracted after each use into a refrigerated part of the machine. The problem of this device for example is that the user needs to handle this outlet and draw it back to the refrigerated position, after each use. Moreover, once cleaning needs to be done, the suction line needs to be removed and cleaned or disposed, which is either complicated or costly. Moreover, cleaning of the nozzle and outlet is complicated and does not provide satisfactory results.
Therefore, it would be desirable to provide a milk foaming device that allows simplified cleaning (only simplified cleaning of very few parts of the device is needed once a day) and simplified handling, avoiding complex cleaning needed in solutions in the prior art and avoiding any rinsing cycles.
The present invention comes to provide a solution to the above-described needs, as it will be further explained. The invention also aims at other objects and particularly at the solution of other problems as will appear in the rest of the present description.